Methylenepyran based dipolar and quadrupolar dyes: synthesis, electrochemical and photochemical properties

Redox-switching of ternary Ni(ii) and Cu(ii) complexes: synthesis, experimental and theoretical studies along with second-order nonlinear optical properties

“…18,24,33 Our interest in the incorporation of the PyMP ligand into complexes 1-4 focused on the fact that under electrochemical oxidative stimuli the methylenepyran fragment was likely to dimerize into bispyrylium species, which in turn could be reduced back to the initial methylenepyran compound. This reversible electron-induced C-C making/breaking bond was already studied by our group, 20,22,36 and others. 37 Recently, we have conducted a spectroelectrochemical study on a series of phenylmethylenepyran organic molecules where the phenyl group was substituted at the para-position by different groups R (R = H, Br, NO2, CO2Me, NMe2, OMe).…”

Incorporation of a ferrocene unit in the π-conjugated structure of donor-linker-acceptor (D-π-A) chromophores for nonlinear optics (NLO)

“…[10][11][12][13][14][15] properties are directly related to the intramolecular charge transfer (ICT) occurring in such structures and can be easily tuned by varying the nature of the donor/acceptor couple and the π-conjugated spacer. [16][17][18] In our group, we have recently optimized the NLO properties of chromophores based on pyrimidine [19][20][21][22][23][24] and/or pyranylidene [22][23][24][25][26][27] moieties as electron-withdrawing and electrondonating fragments respectively. It has been shown that pyrimidine and methylated pyrimidinium salts exhibit higher electron-withdrawing character than well-known pyridine analogues.…”

Reversible Redox Switching of Chromophoric Phenylmethylenepyrans by Carbon–Carbon Bond Making/Breaking

“…26,[33][34][35] γ-methylenepyran compounds are organic chromophores which have been recently integrated as donors in push-pull devices for applications in non-linear optics and photovoltaic cells. [36][37][38][39] Interestingly, electrochemical studies have shown that methylenepyran compounds can undergo fast dimerization by σ C−C bond making upon oxidation at moderate potential values (E p ~ 0.3 V vs. Fc) in organic solvents. 37,38,40,41 The resulting bispyrylium species is reduced irreversibly around −0.8 V vs. Fc leading back to the initial methylenepyran by C−C bond breaking (Scheme 1).…”

“…[36][37][38][39] Interestingly, electrochemical studies have shown that methylenepyran compounds can undergo fast dimerization by σ C−C bond making upon oxidation at moderate potential values (E p ~ 0.3 V vs. Fc) in organic solvents. 37,38,40,41 The resulting bispyrylium species is reduced irreversibly around −0.8 V vs. Fc leading back to the initial methylenepyran by C−C bond breaking (Scheme 1). [40][41][42][43] Bispyrylium compounds are much less sensitive to self-deprotonation than their bisdithiolium analogues.…”